The use of membranes to effect separation of gas/gas, liquid/liquid, and liquid/solid mixtures and solutions has achieved general industrial applicability by various methods, among them being ultrafiltration, hyperfiltration, reverse osmosis and dialysis. In general, membrane elements associated with these processes are contained in vessels called modules, comprising a container having various inlet and outlet ports and an assembly of membranes within said container. The internal configurations are so arranged as to permit the introduction of a feed stream with or without pressure on the upstream face of the membranes, means for collecting permeate which passes through the membranes and emerges on their downstream faces, and means for keeping feed and permeate materials from commingling.
Membranes have been fabricated in various shapes, such as (1) flat sheets which may be supported in a typical plate and frame structure similar to a filter press; (2) flat sheets rolled into spirals with spacing materials interleaved with the membrane and the assembly sealed to provide spiroidal channels permitting the passage of a feed on one side of the coiled membrane through spaces to the opposite side of the membrane; (3) as tubes lining the inner surface of a reinforced braid, the braid itself at times being a component in a larger tube; and (4) in the form of open-ended hollow fibers so organized and sealed into header plates as to provide a separation of the flows over the external surfaces of the hollow fibers from any flow within the bores of the hollow-fibers ensuing by virtue of passage of permeant across the membrane.
Of particular interest is the use of hollow fibers assembled in modular form to provide the desired separation.
In U.S. applications for Letters Patent Ser. No. 943,738 filed Sept. 19, 1978, now U.S. Pat. No. 4,207,192, Ser. No. 943,739 filed Sept. 19, 1978, Ser. No. 943,793 filed Sept. 19, 1978, now U.S. Pat. No. 4,210,536 and Ser. No. 956,032 filed Oct. 30, 1978, now U.S. Pat. No. 4,220,489, various techniques for the selection and winding of hollow fibers and the fabrication and assembly of such fibers into modular form is taught. It is noted that a significant consideration in this work is the manner and means of terminating the hollow fibers so that the ends can be opened to allow for recovery of material within the hollows of the fibers and at the same time provide suitable support to resist the thrust forces developed by the internal pressures within the module shell. In the applications for Letters Patent identified above, the proper use of potting compound solidified about fiber ends with silica taken therein to expose the fiber bores while providing adequate support to resist internal pressure is taught. The provision of recesses of proper configuration and position in the potting compound within which the fiber ends are disposed is illustrated.
It was found however that the necessary proper configuration and position of recess could be achieved only with great difficulty and consumption of time and that repetition could not be achieved with accuracy by the use of known methods and equipment.